Prevention of coil breaks



March 5, 1963 T. sENDzlMxR 3,079,975

PREVENTION oF con. BREAKS Filed July 2, 1956 alf-' jo if s 22 M lllill Il 44 l E .6. ,5 zz i3@ 54 I /16 ff L; Liri'. f@ 22 33 1.,4 23- .5' I f H f4 2 5 J L`: l

d@nite tte Some metals, such for example as low carbon steel after annealing, do not give uniformly over the whole stressed area when stressed beyond their yield point, but yield first along spaced, irregular lines roughly perpendicular to the direction of the stress. rThis may produce a defective surface appearance. The same phenomenon, when an attempt is made to bend a metal sheet, may produce a sharp break -in direction rather `than a smooth conformation to the desired shape. Thus it may be found impossible to form the material into a smooth cylinder, because sharp bends occurring therein tend to give it a multi-lateral configuration. Metals having such defects are generally said to be subject to coil breaks as a matter of convenient terminology.

This objectionable behavior of the metal is manifest, for example, in processes for continuously coating cold rolled low carbon steel strip with molten coating metal, which processes involve high temperature annealing. As examples of such procedures reference is made to United States Patents 2,110,893, 2,136,957, and 2,197,622 in the name of Tadeusz Sendzimir. After coating the strip is rapidly cooled and finally coiled or cut up into sheets which may be subject to coil breaks as set forth.

To eliminate this defect a flexing machine such as a roller leveler has been employed on the coated metal. Providing the gauge of the treated strip is not too light, the use of va roller leveler may be effective in the production of commercially acceptable products. As is well known, the leveler produces coil breaks but at such close intervals that the individual breaks cannot be detected by the eye, or will at least be so close togther as not to interfere with the subsequent use of the product. In general, a leveler which can be depended upon to produce coil breaks separated by not more than three to four times the thickness of the strip will be found satisfactory.

However, for light gauges such as 0.0l inch and below known roller leveiers are not capable of producing coil reaks close enough to one another in the product to make it commercially acceptable. Tension applied to the strip during leveling improves the operation of the device and yet the above named gauge is about the lower limit of permissible operation.

It a primary object of the invention to provide a method and apparatus for flexing `an annealed strip which may be depended upon to alleviate the ditiiculty above discussed even where the strip is of very light gauge.

It is an object of the invention to provide a method and apparatus which, while not limited for use on light gauge strip, will produce a strip which may be bent, formed or subjected to drawing operations without the formation of -coil breaks or that appearance which is frequently termed stretcher strains.

These and other objects of the invention which will -be set forth hereinafter or will be apparent to one skilled in the art upon reading these specifications are accomplished by that construction and arrangement of parts and in that procedure of which an exemplary embodiment will now be described. Reference is made to the accompanying drawings wherein:

FIGURE- l is a side elevation of the exemplary apparatus.

FIGURE 2 is a partial elevation on'an enlarged scale of a portion of the apparatus shown in FIGURE l.

FIGURE- 3 is a partial end elevation taken from the `vight in Fl'GURE l.

Fatented Mar. 5, i953 FIGURE 4 is a partial sectional View taken along the section line 4-4 of FIGURE 3.

FIGURE 5 is a partial sectional view taken along the section line 5 5 of FIGURE 4.

FIGURE 6 is a partial sectional View taken along the section line `6 6 of FIGURE 4.

In the practice of the invention the strip is passed between a small diameter roll properly supported to prevent deflection (or several such rolls) and an elastic medium exerting substantially uniform pressure on the strip parallel to the axis of the roll, the pressure being of sufficient magnitude to bend the strip continuously so as to make it conform to enough of the circumference of the small diameter roll to produce the desired effect.

The action is that of producing coil breaks so close to to one another as to be indistinguishable, the distance between coil breaks being preferably of the order of 0.010 inch to 0.005 inch. Since the apparatus is designed to handle light gauge strip as well as heavier materials, the rolls should be of quite small diameter, say 1/4 inch to 4one inch. These diameters are not necessarily limiting, and it is possible to vary the diameter of the rolls in accordance with the gauge of the strip, especially where the ap paratus is to operate upon a relatively narrow range of gauges. The elastic medium referred to above may be a rubber clad drum or roll of a diameter relatively large in relation to the other rolls.

By way of further preliminary explanation it has been found that in order to facilitate the aligning of the roll in virtual parallelism with the axis of the elastic covered drum, it is preferable to provide an apparatus with two parallel flexing rolls. This results in a geometric arrangement which enables the drum to rest with respect to the rolls, thus making the apparatus self aligning to a certain extent. The strip undergoes the same flexing [treatment twice, which is beneoial.

It is also benecial to tension the strip during treatment; and the greater the tension the less need be the pressure exerted by the elastic element to produce the same results.

Yet another aspect of the invention has to do with introducing fluctuations in the pressure of the elastic medium against the rolls. 'I'he frequency of these fluctuations can be gauged to the desired distance between the coil breaks produced by the apparatus. It has been found that the exertion of fluctuating pressure facilitates an exceedingly close spacing of the coil breaks because it obviates skips where the strip is sporadically subjected to a bending moment under a stress which is not strong enough to produce the required strain. Under conditions of constant pressure the bending moment increases as the strip advances so that the coil breaks may be produced not at a predetermined distance but at some accidental distance coinciding with a point of least resistance in the metal strip. A regular rhythmic surge in the pressure exerted by the elastic medium will cause vthe bends to take place regularly even under the most diiicult conditions.

Referring to the Various figures, the apparatus comprises spaced channel or beam members l and 2 which bear journal bearings 3 and 7 for the shaft extensionsof a drum S which bears on its surface a coating of elastic material 9. The drum 8 may be solid or hollow as desired, but in any event will have suicient stiffness and will be mounted on shafts and in bearings of suitable size to permit the exertion of the desired deilecting pressure. In FIGURE 1 the' drum turns clockwise, and the strip 10 passes approximately 180 about its periphery. Ibis is not a necesary limitation, since it is only necessary that the strip contact the drum in the area of operation of flexing rolls indicated at 11 and l2. The strip may be tensioned in any way desired as by the use of pinch roll combinations or other pulling as retarding devices (not evident.

shown) 'located ahead of and behind the treatment apparatus hereindescribed.

Uprights 13 and 14 are provided at an end of each of the channels 1 and 2. Lever arms 15 and 16 are provided at one end to brackets 17 and 18. The other ends of 'the lever arms are connected by linkages 'to the pistons tof uid pressure cylinders mounted vrespectively on the channels 1 and 2. One of these cylinders vis shown at 19 in VFIGURE '1 the linkage being indicated at 20.

The lever ,arms are interconnected -at Vabout their vcenter portions by a transverse beam 21 of substantial depth and stiffness. The lever arms may be unitary,oreach may be made up of two parts interconnected Yby the-fbeam. The beam may vsupport on vits top-surface a'motor and speed'reducer for driving the exing rolls together with vibrating meanswhere employed. vOnitsf'bottom surface it `bears a ilexing lroll assemblyin'which 'the 'liexing :frlls are supported Ithroughout their working length.

At each end of the `assembly there areplates'122 and 23, The deectingprolls 11 and '12eare journledi'at'their ends in these plates. The 'plates `are fastened ltoV -thennderside of 'the beam 21`as iby means of/'boltsoreyeblts 24 and ,25. Provisionmay'usefully be "made "for'lateral adiustment of theplates `22"and 23. This maybe accomplished by means of Ybolts26 and 27,"the'bolts"being-provided with 'lock nuts and threaded Vinto ears 2-8 and 29 on the beam. The bolts'24 and'ZSmayengage infslotseinthe webs of the beam.

Between the end plates 22 'and 23 there Vis a Iseries of spaced, plate-like supports 30 resting against the beams. The series .may be threaded on shaft-like'members 31 and 32 with the individual plates of the series held in spaced relationship by collars 33 surrounding the shafts. At their ends the shafts 31 and 32 may be threaded and provided with nuts 34 and 35 (FIGURE 5). The plates 30 serve as thrust supports for shafts 36, 37 and 38, on which are journaled series of casters 39, 40 and 41. The Acasters are spaced along the shafts .so as to lie between the plates 30; and the deecting rolls 11 and.12 are, engaged by the casters as best shown Ain FIGURE 4 so as to'be supported throughout their working lengths as will be Any tendency of the thin rolls 11 and 412 to the flexing operation should take place just prior to the coiling ortshearingof the `strip,.i.e. at the point in the line where the strip temperature is lowest. It has been found that if the temperature of the metal during the mechanical working herein taught is too high, the physical properties of the strip and especially .its elongation may suffer. It is also possible with some materials that Vthe phenomenon of fageing may proceed at too -rapid a rate.

In instances where (as shown) the strip 10 follows 'the periphery of the drum 8 for a substantial distance provision may be required for insuring proper tracking of the strip, .especially'where the .strip has or may have a camber,tas often .happens withmaterial rolled on 4-hi mills.: The drumfmaylbe given a .degree of crown, or its axis 'may ibe'made adjustablejn the bearings 3- and 7. Means -for'theadjustment.ofthe.flexingzroll'combination has been .described fabove. .In .the specic Aembodiment 'of the apparatus, 'f a "convenient '.way of iinsuring tracking .Iiesfin l 'the :pressures exerted `by the lever arms 1 '5 tand l16. .I'hisfcan bereadily accomplished by varying lthe fluid pressures .linithe :cylinders V:19.l .It Will :be obvious that the pressure .the low 'pressure side fshould always .be enough 'to iflexstemper-:the ssn-ip; but within this limita tion 'the tracking rcan' .be :readily 'controlled "by dilerental variation of the Ipressures. The tracking is controlled by pressing'the :strip more .or less .into 'the elasticimedium atrones'ide of'the '-strip'as compared with the other. The

tracking may be'madelaut'omatic by lconnecting any known' Y strip position indicator thronghfsuitable servo-mechanisms deflect is taken up by the casters and transferred to `the l seam 21 by the plates so. Themas of Vthe shafts 36,31

a-nd 38 may be mounted .in the end plates 22 and 23,. It is not necessary that they be journaled therein if Athe casters are vmounted rotatably on the shafts. lThe casters may take several forms; but preferably they are short Yrollers mounted by means of ball `or roller bearings on `the shafts. 'Ilse shafts 36, 37 and 38 may have center perforations as shown ,through which lubricant can be vfed to the casters.

It is preferred to drive theflexing rolls 11 and 12. 'To this ,end they may be provided with sprockets 42 and 43 connected by means `of a chain 44 Yto the sprocket 45 of a speed reducer .46. The speed reducer will be driven by a suitable Aelectric motor (not shown) hut also mount- .ed `on the beam 21. It is preferred to drive the rolls through a slip clutch or 4overrurming clutch (47 in FIG- URE 3) which willkeep the vrolls turning Vat Aa minimum speed while leaving them free to attempt a faster speed 4SilQuld .conditions require. A tightner for the chain 44 may be provided as at 48.

When fluid pressure lis applied tothe cylinders A19, a corresponding force multiplied by the leverage .of the leverarms 15 and 16, will be applied to the ilexing rolls 1l and 12 to force .them into the elastic covering 9 f the -drum 8. Strip 10 is flexed by the rolls 1 1 and 12 as most clearly shown in FIGURE 4, thereby producing the V necessary tempering effect to avoid subsequent coil breaks.

By the means indicated a strip subject to coil breaks may be successfully treated for the elimination of this defect even though .of very light gauge. Where the'strip has been coated with molten metal or has been annealed,

to-pressure control 4means for Vthe cylinders. A typical strip positioning indicator is a light roller contacting the edge ofthe strip under light spring pressure.

The value of the :use `ofvibration or deliberately 'pro.

duced uctuations of pressure has already been indicated.v Such variations in pressure may conveniently be attained by .attaching tothe beam v21 a suitable vibrator .(not shown). The vibrator may beany suitable mechanical, pneumatic, magnetic or electric device. Satisfactory results have also 'been iattainedby using .ilexingrolls having a degree of chatter such as may be .involuntarily obtained in grinding `such rolls. In attempting .to 'produce chatter the rolls may be tinted in grinding with a minute pitch, or a similar treatment could .be applied tothe surfaces of the casters.

Rolls which are characterized by chatter and are fluted so as to lhave a polygonal section vhave a higher coeicient of friction while in Acontact with the strip than smooth rolls. Under these circumstances the drive for the flexing rolls may be omitted. The drive is usually provided as a safety measure to prevent the small ilexing rolls -skidding on the surface of the strip. Rolls which are rough, and especially iluted rolls, have `suiiicient coecient of friction to be safe in this regard. As indicated above the drive need not be precisely timed, and preferably vincludes an overrunning clutch 47, enabling the rolls to adopt a higher speed as determined by the strip. Yet if the drive by contact with the strip shouldfail because the strip is too slippery, the chain drive takes over until drive by the strip is re-established.

Instances may -be encountered lin which a uniform degee of deflection is not desirable across the Aentire width of the strip. For example, in galvanized strip there may be a heavier deposit of zinc at the edges. Ihus thatl degreeV of deflection which is desirable in the midsection of the strip may produce over-rolling .at the edges which, if permitted to continue, would kinterfere with the guiding of the strip or the desired qualities of the nal product.

A s set forth above, the surface ofthe elastic medium on the drum may be contoured or the small rolls may be tapered near their' ends or otherwise profiled to the most ection. Any or all of these expedients may be employed.

Modications may be made in the invention without departing from the spirit of it. The effect desired can be obtained through the use of a single iiexing roller operating against an elastic medium. For reasons given above two parallel rollers are preferred. But additional rollers may be employed if desired. The invention having been described in an exemplary embodiment, what is claimed as new and desired to be secured by Letters Patent is:

1. A process of treating light gauge metallic strip of substantial width to produce a strip that is virtually free from coil breaks in subsequent treatment, which process comprises passing a strip having a gauge not substantially greater than 0.015 in. between an elastic medium on one side and a small diameter roll on the other, the diameter of said roll being substantially .25 to 1.0 in. and chosen in accordance with the gauge of the strip to control the spacing of the breaks formed therein, said roll having a length at least equal to the Width of the strip being treated, exerting pressure between the said roll and the elastic medium such as to cause the strip to compress the elastic medium and thereby be caused to conform for a limited arc to the periphery of the small roll, and supporting the small roll throughout its working length to minimize deilection thereof in all directions, whereby to produce in said strip a continuous succession of coil breaks lying close together and substantially parallel to each other, including the step of varying the said pressure periodically at a frequency related to the travel of the strip such as to produce breaks of a desired separation.

2. The process claimed in claim 1 in which the fluctuation of pressure is accomplished by vibrating means acting through the said small diameter roll.

3. The process claimed in claim 1 in which the uctuation of pressure is accomplished in part at least by the provision of a non-circular roll surface.

4. A process of flex-tempering metal strip which ccmprises passing the said strip over the surface of a rotating drum covered with an elastic medi-um and pressing the said strip into the said elastic medium from its side oposite the elastic medium by means of at least one small diameter roll while maintaining said roll against exing throughout its elective working length, and controlling the tracking of said -strip while being so treated, by differentially controlling the said pressure at opposite ends of the eective working length of said roll.

5. In apparatus for the purpose described, an elasticcovered rotary drum of relatively large diameter, and having a width sufficient to accommodate wide, thin-gauge metallic strip, at least two ilexing rolls each having a diameter of substantially 0.25 to 1.0 inch and a length at least equal to the Width of said rotary drum, said exing rolls being axially disposed with respect to said drum, means for supporting said flexing rolls throughout their working length to minimize deflection in all directions, said means comprising a beam extending axially of said drum and mounting sets of casters contacting each of said flexing rolls, means urging said flexing rolls against said drum under su'icient pressure so that, when a metallic strip is interposed between said ilexing rolls and said drum, saidstrip will be caused to compress said elastic to cause said strip to conform to limited arcs of the peripheries of said flexing rolls, whereby coil breaks will be formed in said strip lying uniformly close together, and vibrating means attached to said beam.

6. In apparatus for the purpose described, an elasticcovered rotary drum of relatively large diameter, having a width sucient to accommodate wide, thin-gauge metallic strip, at least two spaced exing rolls each having a diameter of substantially 0.25 to 1.0 inch and a length at least equal to vthe width of said rotary drum, said exing rolls being axially disposed with respect to said drum, means supporting said flexing rolls throughout their working length to minimize deilection in all directions, said means including a beam extending axially of said drum and mounting sets of casters contacting said flexing rolls, means urging said exing rolls against said drum under suicient pressure so that, when a metallic strip is interposed between said tlexing roll and said drum, said strip will be caused to compress said elastic to cause said strip to conform to limited arcs of the peripheries of said ilexing rolls, whereby coil breaks will be formed in said strip lying uniformly close together, at least one rotating element other than said drum being of non-circular cross section productive of chatter.

7. In apparatus for the purpose described, an elasticcovered rotary drum of relatively large diameter, having a width suiiicient to accommodate wide, thin-gauge metallic strip, at least two spaced flexing rolls each having a diameter or" substantially 0.25 to 1.0 inch and a length at least equal to the width of said rotary drum, said ilexing rolls being axially disposed with respect to said drum, means supporting said flexing rolls throughout their working length to minimize deflection in all directions, said means including a beam extending axially of said drum and mounting sets of casters contacting said exing rolls, means for driving said ilexing rolls, and means urging said flexing rolls against said drum under sufcient pressure so that, when a metallic strip is interposed between said llexing rolls and said drum, said strip will be caused to compress said elastic to cause said strip to conform to limited arcs of the peripheries of said flexing rolls, whereby coil breaks will be formed in said strip lying uniformly close together.

8. The structure claimed in claim 7 including means for adjustably positioning the said exing rolls to align them with respect to the axis of said drum.

9. In apparatus for the purpose described, an elasticcovered rotary drum of relatively large diameter, having a width suicient to accommodate wide, thin-gauge metallic strip, at least one exing roll of relatively small diameter and of a length at least equal to the width of said rotary drum, said tlexing roll being axially disposed with respect to said drum, means supporting said exing roll throughout its working length to minimize deflection in all directions, said means including a beam extending axially of said drum and sets of casters thereon contacting said flexing roll, and means for urging said flexing roll toward said drum under pressure, said apparatus having a base in which said drum is journaled, said urging means comprising a pair of spaced levers, one at each end of said beam, said levers being mounted at one end pivotally on said base, said beam being mounted at its ends on central portions of said levers and each lever having a separately actuable tensioning means connecting its other end with said base, whereby the pressure exerted by said lexing roll may be differentially controlled at the opposite ends of the effective Working length of said roll to control the tracking of metallic strip passing through said apparatus.

References Cited in the le of this patent UNITED STATES PATENTS 175,365 Marshall Mar. 28, 1876 447,295 Brenner Mar. 3, 1891 1,032,907 Hyde July 16, 1912 1,854,021 Derby Apr. 12, 1932 1,930,562 Krueger Oct. 17, 1933 2,059,993 Hanson Nov. 3, 1936 2,060,400 Nieman Nov. 10, 1936 2,176,872 Hennessy Oct. 24, 1939 2,273,122 Maussnest Feb. 17, 1942 2,486,844 Hercik Nov. 1, 1949 2,612,934 Dubosclard Oct. 7, 1952 

1. A PROCESS OF TREATING LIGHT GAUGE METALLIC STRIP OF SUBSTANTIAL WIDTH TO PRODUCE A STRIP THAT IS VIRTUALLY FREE FROM COIL BREAKS IN SUBSEQUENT TREATMENT, WHICH PROCESS COMPRISES PASSING A STRIP HAVING A GAUGE NOT SUBSTANTIALLY GREATER THAN 0.015 IN. BETWEEN AN ELASTIC MEDIUM ON ONE SIDE AND A SMALL DIAMETER ROLL ON THE OTHER, THE DIAMETER OF SAID ROLL BEING SUBSTANTIALLY .25 TO 1.0 IN. AND CHOSEN IN ACCORDANCE WITH THE GAUGE OF THE STRIP TO CONTROL THE SPACING OF THE BREAKS FORMED THEREIN, SAID ROLL HAVING A LENGTH AT LEAST EQUAL TO THE WIDTH OF THE STRIP BEING TREATED, EXERTING PRESSURE BETWEEN THE SAID ROLL AND THE ELASTIC MEDIUM SUCH AS TO CAUSE THE STRIP TO COMPRESS THE ELASTIC MEDIUM AND THEREBY BE CAUSED TO CONFORM FOR A LIMITED ARC TO THE PERIPHERY OF THE SMALL ROLL, AND SUPPORTING THE SMALL ROLL THROUGHOUT ITS WORKING LENGTH TO MINIMIZE DEFLECTION THEREOF IN ALL DIRECTIONS, WHEREBY TO PRODUCE IN SAID STRIP A CONTINUOUS SUCCESSION OF COIL BREAKS LYING CLOSE TOGETHER AND SUBSTANTIALLY PARALLEL TO EACH OTHER, INCLUDING THE STEP OF VARYING THE SAID PRESSURE PERIODICALLY AT A FREQUENCY RELATED TO THE TRAVEL OF THE STRIP SUCH AS TO PRODUCE BREAKS OF A DESIRED SEPARATION. 